Laminated radiation member, power semiconductor apparatus, and method for producing the same

ABSTRACT

A laminated radiation member includes a radiation plate, an insulation substrate bonded to the upper surface of the radiation plate and an electrode provided on the upper surface of the insulation substrate. The laminated radiation member is made by a method including the steps of surface treating a bonding surface of the radiation plate and/or the insulation substrate, interposing ceramic particles surface treated to assure wettability with a hard solder or a metal between the radiation plate and the insulation substrate, disposing a hard solder above and/or below the ceramic particles, heating the hard solder to a temperature higher than the melting point of the solder, penetrating the molten hard solder into spaces between the ceramic particles to react the ceramic particles with the solder to produce a metal base composite material, and bonding the radiation plate and the insulation substrate with the metal base composite material.

CROSS REFERENCE TO RELATION APPLICATIONS

This application is a Continuation application of U.S. application Ser.No. 10/242,862 filed Sep. 13, 2002, now abandoned which is a Divisionalapplication of U.S. application Ser. No. 09/774,206 filed Jan. 30, 2001,now U.S. Pat. No. 6,485,816, the entireties of which are incorporatedherein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a laminated radiation member, a powersemiconductor apparatus, and a method for making the same.

A known power semiconductor apparatus is, for example, one which iscomposed of the main part as shown in FIG. 4. In FIG. 4, 101 indicates apower semiconductor apparatus, 102 indicates a semiconductor chipcomprising IGBT or the like, 103 indicates a metal base plate forradiating the heat generated from the semiconductor chip 102, 104indicates a ceramic plate comprising aluminum nitride or the like forinsulating the semiconductor chip 102 from the metal base plate 103, 105a indicates a first metal electrode provided above the upper surface ofthe ceramic plate 104, 105 b indicates a second metal electrode providedbelow the lower surface of the ceramic plate 104, 106 a indicates afirst hard solder paste for bonding the ceramic plate 104 to the firstmetal electrode 105 a, 106 b indicates a second hard solder paste forbonding the ceramic plate 104 to the second metal electrode 105 b, 107 aindicates a first solder for bonding the semiconductor chip 102 to thefirst metal electrode 105 a, 107 b indicates a second solder for bandingthe metal base plate 103 to the second metal electrode 105 b, 108 aindicates a first metal wire comprising aluminum to be connected to thesemiconductor chip 102, 108 b indicates a second metal wire comprisingaluminum to be connected to the first metal electrode 105 a, and 109indicates a silicone gel which covers the semiconductor chip 102, theceramic plate 104, the first metal electrode 105 a and the second metalelectrode 105 b and seals them.

The conventional power semiconductor apparatus having the aboveconstruction is usually made by the following method. In the case ofmaking the conventional power semiconductor apparatus 101, first, hardsolder pastes, which are the first and second hard solder pastes 106 aand 106 b, are printed at a given thickness on both surfaces of theceramic plate 104. Then, two metal electrodes, which are the first andsecond metal electrodes 105 a and 105 b, are put on the hard solderpastes printed on both the surfaces of the ceramic plate 104 and heattreated at a given temperature, for example, about 850° C., therebybonding the first and second metal electrodes to both surfaces of theceramic plate 104.

Thereafter, the ceramic plate 104, to both surfaces of which the metalelectrodes are bonded is bonded, to the metal base plate 103 with ahigh-temperature solder (melting point: about 260° C.) which is thesecond solder 107 b, and the semiconductor chip 102 is bonded with alow-temperature solder (melting point: about 150° C.), which is thefirst solder 107 a, to both surfaces of the ceramic plate 104 on whichthe metal electrodes are bonded. A metal wire, which is the first metalwire 108 a, is connected to the semiconductor chip 102 by wire bonding,and a metal wire, which is the second metal wire 108 b, is connected tothe metal electrode which is the first metal electrode 105 a by wirebonding.

Usually, the metal base plate 103 on which the semiconductor chip 102,the ceramic plate 104, the first metal electrode 105 a and the secondmetal electrode 105 b, and the like are mounted is contained in apackage. Silicone gel 109 is vacuum injected into the package and curedby heating, whereby the semiconductor chip 102, the ceramic plate 104,the first metal electrode 105 a and the second metal electrode 105 b,and the like are covered with the silicone gel 109 and sealed. In thisway, the conventional power semiconductor apparatus 101 is made.

However, since the insulation substrate (104) and the metal electrodes(105 a,b) are bonded with the hard solders (106 a,b), cracks occur dueto the difference in expansion coefficient between the insulationsubstrate, which has a low thermal expansion coefficient, and the hardsolders and metal electrodes, which have high thermal expansioncoefficients. Furthermore, since the insulation substrate (104) and theradiation plate (103) are connected with solder, there is the problem ofhigh thermal resistance.

On the other hand, as an example of using no solder for bonding of aninsulation plate and a radiation plate, JP-A-11-269577 proposes a methodof forming a metal base composite material having a heat sink functionby a chemical process utilizing a reaction between a ceramic dispersionmaterial and a molten metal. This method suffers from the problem thatsince the molten metal is high-pressure injected into the ceramicdispersion material, expensive facilities are required, causing anincrease of cost. There may be considered a means to carry out thereaction under impregnating the ceramic dispersion material with moltenmetal, but in this case, there is the problem that the penetrating speedis slow. In this method, the insulation substrate and the metal basecomposite material as a radiation plate are connected with a metal filmor are connected with disposing a compound containing a firing aid forthe insulation substrate at the bonded surface between the insulationsubstrate and the metal film, and therefore the thermal conductivity isbetter than the case of connecting with a solder. However, occurrence ofcracks caused by difference in thermal expansion coefficient between theinsulation plate of low thermal expansion coefficient and the metal filmof high thermal expansion coefficient or the metal film provided with acompound containing firing aid for the insulation substrate cannotsometimes be avoided.

As an example of using no metallic radiation plate, there is, forexample, an aluminum-silicon carbide composite material known as a metalceramics composite material. This composite material is generallyprepared by making a molded body (preform) of ceramic particles, ceramicfibers, whiskers, etc., then impregnating the preform with a moltenmetal and cooling it. As the method for impregnating with molten metal,there are various known methods such as a method based on powdermetallurgy, a method according to high-pressure casting, e.g., diecasting (JP-A-5-508350), a melt forging method (“Material,” Vol. 36, No.1, 1997, pages 40–46), spontaneous penetrating method (JP-A-2-197368),etc.

On the other hand, as power semiconductor apparatuses, there are known,for example, those which comprise a semiconductor chip comprising IGBTor the like, a metal base plate of about 4 mm thick comprising copper orthe like for radiating heat generated from the semiconductor chip, and aceramic plate of about 0.6 mm thick comprising aluminum nitride or thelike for insulating the semiconductor chip from the metal base plate. Afirst metal electrode of about 0.4 mm thick comprising copper or thelike is bonded to the upper surface of the ceramic plate with a firsthard solder of a given thickness. A semiconductor chip is bonded to theupper surface of the metal electrode with a solder of about 0.2 mmthick. A second metal electrode of about 0.2 mm thick comprising copperor the like is bonded to the under surface of the ceramic plate with asecond solder of a given thickness. The under surface of the ceramicplate and the second metal electrode are bonded to the radiation platewith a solder or a hard solder.

However, there is a problem of low radiation property because theinsulating ceramic substrate and the radiation plate are connected witha solder. Moreover, in the case of bonding the insulating ceramicsubstrate and the metallic heat sink material with a hard solder byactive metal method or the like, cracks caused by thermal stress at thetime of bonding occur on the side of the insulating ceramic substratebecause of the great difference in thermal expansion coefficient betweenboth the materials. Furthermore, a multi-layer type bonded body, whichis bonded with a solder and provided with a stress relaxing layer by ameans other than soldering, is low in endurance when exposed to thermalcycles of cooling-heating and, besides, increases in thermal resistancedue to the increase of bonded interfaces which inhibits radiation.Moreover, since stress relaxation is conducted by employing amulti-layer structure, the number of production steps necessarilyincreases, and, as a result, this causes an increase of production cost.This is a serious problem.

On the other hand, as a method of bonding different members, theapplicant of the present application disclosed in applicationJP-A-11-228245, utilizing an adhesive composition comprising ceramicfine particles and a hard solder and capable of reducing thermal stress.However, the object of the invention disclosed in the above applicationis to inhibit the decrease of bonding strength and the occurrence ofcracks during the cooling operation, mainly after bonding, in makingmembers by bonding the different members and need airtightness. Thepatent application makes no mention which suggests improvement ofendurance in a use environment, such as increasing peeling resistanceand effectively inhibiting cracking at bonded portions under severethermal cycles, where high temperature-low temperature with coolingoperation is repeated many times, in applications such as heat sinks,laminated radiation members and power semiconductor apparatuses. Thatis, of course, the application does not have descriptions suggestingthat the products can function as a bonding layer of heat sinks,laminated radiation members and power semiconductor apparatuses.

SUMMARY OF THE INVENTION

As mentioned above, the object of the present invention is to provide alaminated radiation member as a power semiconductor apparatus which issubstantially free from cracks generated due to a difference in thethermal expansion coefficient between an insulation substrate and aradiation plate, and which is excellent in radiation properties andthermal cycle characteristics, and a method for making the laminatedradiation member.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view of a water cooling module used in the test.

FIG. 2 is a sectional view showing the construction of the main part ofthe power semiconductor apparatus according to the present invention.

FIG. 3 is a sectional view of a mold used in the production of examplesof the power semiconductor apparatus according to the present invention.

FIG. 4 is a sectional view showing the construction of the main part ofa conventional power semiconductor apparatus.

In the drawings, the following reference numerals represent:

(1) Circuit electrode; (2) Bonding layer (metal base compositematerial); (3) Insulation substrate; (4) Radiation plate; (5) Mixture ofceramic particles and active metal; (6) Mold; (7) Solder; (8)Semiconductor chip; (9) Metal wire; (10) Insulating sealer; (11) Heater;(12) Module; (13) Flow path; (14) Water bath with pump; and (15) Flowmeter.

DETAILED DESCRIPTION OF THE INVENTION

As a result of intensive research conducted by the inventors in anattempt to attain the above object, it has been found that a laminatedradiation member which is substantially free from cracking caused by adifference in the thermal expansion coefficient between an insulationsubstrate and a radiation plate, and which is excellent in radiationproperties, can be produced by forming a metal base composite materialusing a specific ceramic dispersion material and a hard solder, andbonding an insulation substrate and a radiation plate with the metalbase composite material interposed between them. Thus, the presentinvention has been accomplished.

That is, firstly, the present invention provides a laminated radiationmember comprising a radiation plate, an insulation substrate bonded tothe upper surface of the radiation plate and an electrode provided onthe upper surface of the insulation substrate, wherein the radiationplate and the insulation substrate are bonded with a metal basecomposite material in which ceramic particles are dispersed and which ispresent between the radiation plate and the insulation substrate.

The present invention further provides a laminated radiation member,wherein the metal base composite material layer is produced by providingceramic dispersion particles which are previously surface treated so asto assure wettability with a hard solder or a metal, and reacting theceramic particles with the molten solder or metal and penetrated betweenthe ceramic dispersion particles. The reaction is carried out in thespace between the radiation plate, the bonding surface of which may be,if necessary, previously surface treated so as to assure wettabilitywith the solder or the metal, and the insulation substrate, the bondingsurface of which may also be, if necessary, previously surface treatedso as to assure wettability with the solder or the metal.

The present invention further provides a laminated radiation member,wherein the metal base composite material layer is produced by reactingthe ceramic dispersion particles with a hard solder or a metal moltenpenetrated between the ceramic dispersion particles. The solder or metalfurther contains at least one of an active metal selected from the groupconsisting of Ti, Zr, Nb, Ta and Hf, or, the active metal powders arepreviously dispersed in the space between the ceramic dispersionparticles. The laminated radiation member is characterized in that theinsulation substrate comprises aluminum nitride or silicon nitride andfurther characterized in that the insulation substrate and the electrodeprovided on the upper surface of the insulation substrate are bondedwith the metal base composite material layer in which ceramic particlesare dispersed and which is interposed between the insulation substrateand the electrode.

Secondly, the present invention provides a power semiconductor apparatuscomprising a circuit electrode, a laminated radiation member comprisinga radiation plate and an insulation substrate, a semiconductor chipbonded to the circuit electrode formed at the laminated radiation memberand a metal wire electrically connected to the semiconductor chip, thesemiconductor chip, the laminated radiation member and the circuitelectrode being sealed with an insulation sealer, characterized in thatthe laminated radiation member is one of the laminated radiation membersenumerated above.

Thirdly, the present invention provides a method for making a laminatedradiation member comprising a radiation plate, an insulation substratebonded to the upper surface of the radiation plate and an electrodeprovided on the upper surface of the insulation substrate. The methodincludes a step of, if necessary, previously surface treating a bondingsurface of the radiation plate and/or the insulation substrate so as toassure wettability with a hard solder or a metal, a step of interposingceramic particles previously surface treated so as to assure wettabilitywith a hard solder or a metal between the radiation plate and theinsulation substrate, a step of disposing a hard solder above and/orbelow the ceramic particles, a step of heating the solder to atemperature higher than the melting point of the solder to melt thesolder, a step of penetrating the molten solder into spaces between theceramic particles to react the ceramic particles with the solder toproduce a metal base composite material, and a step of bonding theradiation plate and the insulation substrate with the metal basecomposite material present between them.

The present invention further provides a method for making a laminatedradiation member, wherein the surface treatment of the ceramic particlesand/or the insulation substrate and/or the radiation plate for assuringthe wettability, is a coating treatment of at least a part of thesurface with a metal. This treatment is electroless plating, plating,sputtering, chemical vapor deposition, vacuum deposition, or ionicplating. The method for making a laminated radiation member comprising aradiation plate, an insulation substrate bonded to the upper surface ofthe radiation plate and an electrode provided on the upper surface ofthe insulation substrate, is further characterized by including a stepof interposing the ceramic particles between the radiation plate and theinsulation substrate, a step of disposing a hard solder containing atleast one of an active metal selected from the group consisting of Ti,Zr, Nb, Ta and Hf above and/or below the ceramic particles, a step ofheating the solder to a temperature higher than the melting point of thesolder to melt the solder, a step of penetrating the molten solder intospaces between the ceramic particles to react the ceramic particles withthe solder to produce a metal base composite material, and a step ofbonding the radiation plate and the insulation substrate with the metalbase composite material present between them.

The present invention further provides a method for making a laminatedradiation member comprising a radiation plate, an insulation substratebonded to the upper surface of the radiation plate and an electrodeprovided on the upper surface of the insulation substrate, including astep of interposing ceramic particles and active metal powders selectedfrom the group consisting of Ti, Zr, Nb, Ta and Hf between the radiationplate and the insulation substrate, a step of disposing a hard solderabove and/or below the ceramic particles, a step of heating the solderto a temperature higher than the melting point of the solder to melt thesolder, a step of penetrating the molten solder into spaces between theceramic particles to react the ceramic particles with the solder toproduce a metal base composite material, and a step of bonding theradiation plate and the insulation substrate with the metal basecomposite material present between them.

In addition, the present invention provides a method for making alaminated radiation member comprising a radiation plate, an insulationsubstrate bonded to the upper surface of the radiation plate and anelectrode provided on the upper surface of the insulation substrate,including a step of placing the insulation plate in a solidificationmold, a step of disposing ceramic particles on one surface of theinsulation substrate, a step of pouring a molten metal into thesolidification mold to impregnate the ceramic particles with the moltenmetal and, simultaneously with the impregnation, pouring the moltenmetal into the portion where the ceramic particles are not present, anda step of solidifying the molten metal to form the radiation plate inthe portion where the ceramic particles are not present. The method isfurther characterized by including a step of bonding the insulationsubstrate and the electrode with a hard solder or a metal base compositematerial present between them, simultaneously with the heat treatmentfor bonding the radiation plate and the insulation substrate with themetal base composite material present between them.

The present invention further provides a method for making a laminatedradiation member, characterized by further including a step of bondingthe electrode to the insulation substrate with the hard solder or themetal base composite material by a heat treatment at a temperature lowerthan the temperature at the bonding step of the radiation plate and theinsulation substrate, the insulation substrate being bonded to theinsulation substrate with the metal base composite material presentbetween them. A method for making a laminated radiation member is alsoprovided, including a step of forming an electrode at a temperaturelower than the temperature at the bonding step of the radiation plateand the insulation substrate on the insulation substrate bonded to theradiation plate with the metal base composite material. A method formaking a laminated radiation member is provided, characterized in thatthe step of forming the electrode at a lower temperature compriseselectroless plating, plating, sputtering, ionic plating, chemical vapordeposition, vacuum deposition or flame spraying, or combination of them.

Fourthly, the present invention further provides a method for making apower semiconductor apparatus, including a step of bonding asemiconductor chip to an electrode of a laminated radiation membercomprising a radiation plate, an insulation substrate bonded to theupper surface of the radiation plate and an electrode provided on theupper surface of the insulation substrate, the radiation plate and saidinsulation substrate being bonded to each other with a metal basecomposite material layer in which ceramic particles are dispersed andwhich is present between the radiation plate and the insulationsubstrate, a step of electrically connecting metal wires to thesemiconductor chip and the electrode, respectively, a step of placing ina package the semiconductor chip, the laminated radiation member and thecircuit electrode, and then providing an insulating sealer in thepackage. Moreover, the present invention provides a method for making apower semiconductor apparatus, characterized in that the laminatedradiation member is made by one of the methods mentioned above as thethird aspect.

According to the above methods of the present invention, bonding of theinsulation substrate and the radiation plate is carried out with themetal base composite material layer present therebetween. That is, thedesired laminated radiation member and power semiconductor apparatus,which are excellent in thermal conductivity and thermal cyclecharacteristics, can be obtained by a step of, if necessary, previouslysurface treating a bonding surface of the radiation plate and/or theinsulation substrate so as to assure wettability with a hard solder or ametal, a step of interposing ceramic particles previously surfacetreated so as to assure wettability with a hard solder or a metalbetween the radiation plate and the insulation substrate, a step ofdisposing a hard solder above and/or below the ceramic particles, a stepof heating the solder to a temperature higher than the melting point ofthe solder to melt the solder material, a step of penetrating the moltensolder into spaces between the ceramic particles to react the ceramicparticles with the solder to form a metal base composite material low inthermal resistance and high in radiation properties as a bonding layer,and a step of bonding the radiation plate and the insulation substratewith the metal base composite material present therebetween.

The present invention will be explained in more detail below. The term“metal base composite material layer” in the present specification meansa layer comprising a composite material which can be produced by meltingand mixing a hard solder and ceramic particles subjected to a specificsurface treatment and capable of reducing a specific thermal stress.

The laminated radiation member as a power semiconductor apparatusaccording to the present invention can be made in the following manner.A ceramic dispersing material previously subjected to plating, such asSiC particles subjected to Ni—B plating treatment, is placed on a platedsurface of a radiation plate which may be previously subjected toplating treatment. A pressure is applied thereto to reduce the thicknessand increase packing rate of the particles. A hard solder such as aBA4004 (Al-10Si-1.5Mg) sheet, which is an aluminum solder, is placedthereon, and thereon is placed an insulation substrate (both surfaces ofwhich are subjected to plating treatment). Further thereon is placed aceramic dispersing material previously subjected to plating treatment,such as the above SiC particles subjected to Ni—B plating, followed byapplying a pressure and increasing packing rate of the particles.Thereon is placed a hard solder such as a BA4004 (Al-10Si-1.5Mg) sheet,which is an aluminum solder, and further thereon is placed a thin coppersheet for the formation of a circuit. Thereafter, the resulting stack issubjected to a heat treatment at a given temperature in a vacuum and therespective components are bonded with metal base composite materiallayers present therebetween.

In the present invention, as the insulation substrate, ceramicsubstrates having a thickness of 0.1–2 mm may be used, preferably onessuch as aluminum nitride and silicon nitride having a thickness of 0.1–2mm. Especially preferred are silicon nitride substrates disclosed inJP-A-4-212441 and silicon nitride substrates disclosed in JP. Appln.No.11-176479 filed on Jun. 23, 1999 from the points of thermalconductivity and assurance of bonding strength.

The insulation substrate is preferably previously surface treated forassuring wettability with the hard solder. As the dispersing materialscomprising ceramic particles which reduce thermal stress, ceramicparticles, such as SiC, AlN, Si₃N₄, and Al₂O₃, having a particlediameter of preferably 5–200 μm, and more preferably, 10–50 μm, may beused. Usually, they are surface treated for assuring wettability withthe hard solder and uniformly spread over the insulation substrateplaced, for example, in a heat resistant container.

Of course, for bonding of the insulation substrate and the radiationplate, a hard solder comprising at least one metal or metal alloyselected from Al, Al alloy, copper and copper alloy is used togetherwith the ceramic dispersing material for the formation of the bondinglayer. The hard solder disposed above and/or under the particles of theceramic dispersing material is interposed between the radiation plateand the insulation substrate, followed by melting it to form a metalbase composite material which is the bonding layer. Usually, the hardsolder is placed on ceramic dispersing material uniformly spread overthe radiation plate disposed in a heat resistant container, and theinsulation substrate is further mounted thereon, followed by heating andmelting the solder to penetrate it into the spaces between the particlesof the ceramic dispersing material, and solidifying it to form thedesired bonding layer, namely, a metal base composite material. This ispreferably affected by heating to a temperature 50–100° C. higher thanthe melting point of the above-mentioned metal or alloy in a furnace ofvacuum or inert atmosphere. The formation of the bonding layer bypenetration of the metal or the alloy can be completed in a shorter timeas compared with the similar conventional technique utilizing the abovereaction, and, hence, the retention time at the above temperature can benot longer than 10 minutes.

In this case, the surface treatment of the insulation substrate, theradiation plate and the dispersing material, which is the ceramicparticles, can comprise forming a layer of Ni, Cu, Pd, or the like onthe surface of the ceramic dispersing material by electroless plating,plating, sputtering, ion plating, chemical vapor deposition, vacuumdeposition and the like. However, in the case of using mainly Al alloyas the hard solder, electroless Ni plating is suitable. In this case,the thickness of the plating layer is preferably not more than 1 μm,more preferably about 0.5 μm. If the thickness is less than 0.5 μm,penetration of the solder does not properly occur, and if it is morethan 1 μm, thermal conductivity may be deteriorated owing to productionof an intermetallic compound (Al₃Ni) in a large amount.

For the assurance of wettability, it is also possible to add an activemetal such as Ti, Nb, Hf, Ta or Zr to the melt of metal comprising thesolder and forming a nitride, oxide or carbide of these active metals onthe surface of the insulation substrate and the ceramic dispersingmaterial. The amount of the active metal added is suitably 0.5–20% byweight based on the solder. The metal may be previously added to thesolder, but when fine particles of the active metal are previously addedto the ceramic dispersing material, since the amount of the active metalto be added can be smaller, the thermal conductivity of the resultingcomposite material can be maintained at high level. Thus, this ispreferred. This may be combined with the method of subjecting thesurface of the ceramic dispersing material to said plating treatment.

In reacting the ceramic dispersing material with the molten hard solderto form a composite material, when those surface treated by electrolessplating, plating, sputtering, chemical vapor deposition, vacuumdeposition, or ion plating are used, local exothermic reaction (burningsynthesis reaction) takes place in the case of contacting of the surfacetreatment layer with the molten metal to cause reaction. For example, inthe case of the surface treatment layer being an electroless Ni—Bplating and the molten metal being an Al-based alloy, Ni aluminide isproduced in accordance with the reaction formula: Al+Ni→Al₃Ni, and thegenerated heat causes an exothermic reaction. Therefore, substantiallyno pressure is needed, and the wettability between the ceramicdispersing material/the molten metal is markedly improved by theabove-mentioned local exothermic reaction, and, as a result, penetrationspeed of the molten metal is increased and the metal base compositematerial can be formed in a very short time.

Furthermore, when an active metal is utilized for forming a compositematerial of the ceramic dispersing material and the melt of metalconstituting the hard solder, since the active metal (Ti, Zr, Nb, Ta, Hfor the like) is highly active for oxygen, nitrogen and carbon,wettability between the ceramic dispersing material and the molten metalis improved by dissolution of the active metal in the molten metal toform a solid solution, and microscopically an interface reaction withthe melt containing the active metal takes place on the surface of theceramic dispersing material. That is, in the case of the ceramicdispersing material being SiC and the molten metal being Cu—Ti alloy, anexothermic reaction with formation of TiC takes place according to thereaction of SiC+Ti→TiC+Si (in copper). Thus, as above, this localexothermic reaction increases penetration speed of the molten metal, andthe metal base composite material can be produced in a very short time.

As the radiation plate, metallic plates such as of copper, aluminum,silver, and the like, which are generally used for power semiconductorapparatus, or plates made of alloys such as Cu—Be or composite materialssuch as Cu—Mo, Cu—SiC, and the like may be suitably used. In bonding theradiation plates made of composite materials, it is preferred to usethose surface treated by the above methods in the same manner as of thedispersing materials comprising ceramic particles. Formulation of theradiation plates has no limitation, and those of the same as used forother power semiconductor apparatuses can be used without any problems.As to members other than those mentioned above, naturally thosegenerally used in power semiconductor apparatuses can be used withoutany problems.

In the method of the present invention, the electrode can be formedsimultaneously with the bonding of the radiation plate and theinsulation substrate as in the case of Example 1, or it may beseparately formed. When the electrode is formed separately, it can besolder-bonded using a hard solder which melts at lower than the bondingtemperature of the radiation plate and the insulation substrate. In thiscase, the electrode may be bonded with the metal base composite materiallayer in the same manner as in the bonding of the radiation plate andthe insulation substrate. Furthermore, as a method of separate molding,the electrode can also be made freshly by printing, flame spraying,plating or the like, instead of by bonding.

The present invention will be explained in more detail by the followingexamples. These examples should not be construed as limiting theinvention in any manner.

Measurements of characteristics in the examples were conducted by thefollowing methods.

Thermal Cycle Characteristics

In the air, a sample was subjected to cycles, one cycle of whichcomprises holding the sample for 30 minutes in a low temperaturecryostat kept at −40° C., then leaving the sample for 10 minutes in athermostat kept at 25° C., furthermore raising the temperature of thethermostat to 125° C. and holding the sample therein for 30 minutes, andlowering the temperature of the thermostat to 25° C. and leaving thesample therein for 10 minutes. Five samples were prepared for each kindof samples, and the thermal cycle characteristics of the respectivesamples were evaluated in terms of the number of cycles when even one ofthe five had cracks in the insulation substrate or showed separation atthe bonded portion of the radiation plate.

Heat Resistant Characteristics

A water-cooling module as shown in FIG. 1 was made, and a heater wasadhered to the surface of the circuit-formed portion of the insulationsubstrate with an Ag paste. Cooling water of 24° C. was circulated at aflow rate of 2 l/min, and temperatures of the heater surface and theinterface of sample/running water were measured, and heat resistance ofthe sample was calculated. Relative evaluation of the heat resistancewas conducted with assuming the resistance of Comparative Example 1 tobe 1.0.

EXAMPLE 1

Ni Plating Method/Upper Electrode Simultaneous Bonding

As the insulation substrate, a silicon nitride insulation substrate of50 mm×40 mm×0.3 mm having a thermal conductivity of 90 W/mK was preparedby adding Y₂O₃ and MgO as firing assistants to a commercially availablesilicon nitride powder and firing the mixture at a given temperature fora given period. Separately, a radiation plate (80 mm×50 mm×3 mm)comprising a Cu—SiC composite material and having a thermal conductivityof 250 W/mK was prepared by the method disclosed in JP-A-11-029379.

Separately, the surface of commercially available SiC particles (averageparticle diameter: about 50 μm) was subjected to Ni—B plating at athickness of about 0.5 μm by wet electroless plating. On the other hand,both sides of the above silicon nitride insulation substrate weresubjected to electroless Ni—B plating at a thickness of about 1 μm. Oneside of the above Cu—SiC radiation plate was also subjected toelectroless Ni—B plating at a thickness of about 1 μm. The above Ni—Bplated SiC particles were disposed on the Ni—B plated surface of theCu—SiC radiation plate, followed by applying a pressure to reduce thethickness to improve the packing rate of the particles. On the uppersurface thereof was placed an Al solder sheet (BA4004: Al-10Si-1.5Mg)and thereon was placed the silicon nitride insulation substratesubjected to Ni—B plating on both the sides. Furthermore, Ni—B platedSiC particles were disposed on the upper surface thereof, followed byapplying a pressure to reduce the thickness to improve the packing rateof the particles. On the upper surface thereof was placed an Al soldersheet (BA4004: Al-10Si-1.5Mg). Then, a copper sheet 0.3 mm thick wasplaced on the upper surface of the solder sheet.

Then, the resulting stack was heated to 700° C. at a heating rate of 15°C./min in a vacuum of 0.00133 Pa and kept at 700° C. for 3 minutes, andthen slowly cooled to room temperature at a cooling rate of 2° C./min toprepare a bonded body (laminated radiation member). In this bonded body,the Cu—SiC radiation plate and the silicon nitride insulation substratewere bonded with a composite material layer of SiC/aluminum solderpresent between the radiation plate and the substrate, and the siliconnitride insulation substrate and the uppermost copper sheet 0.3 mm thickwere also bonded with a composite material layer of SiC/aluminum solder.

Then, a resist for the formation of circuits was printed on the wholesurface of the thus obtained laminated radiation member, then only theportions which were not etched later were selectively cured, the uncuredportions were removed, and the exposed copper was etched with an aqueouscupric chloride solution to form a circuit pattern of the uppermostcopper sheet of the laminated radiation member. Furthermore, this waswashed with an aqueous acid ammonium fluoride solution and additionallywashed with water several times to remove the solder between thecircuits.

Then, the resist was peeled off and finally the surface of the uppermostcopper sheet (=circuit sheet) was subjected to Ni—P plating to form aprotective layer, thereby making a laminated radiation member.

EXAMPLE 2

Ni Plating Method/Upper Electrode Simultaneous Bonding

A laminated radiation member was made in the same manner as in Example1, except that a commercially available pure copper plate (oxygen-freecopper of pure copper composition or tough pitch copper, 80×50×3 mm:radiation plate) having a thermal conductivity of 390 W/mK was preparedin place of preparing the Cu—SiC composite material (80×50×3 mm:radiation plate), and a commercially available Al₂O₃ powder (averageparticle diameter: about 40 μm) was used in place of the commerciallyavailable SiC particles (average particle diameter: about 50 μm).

EXAMPLE 3

Powder Active Metal Method/Upper Electrode Simultaneous Bonding

A silicon nitride insulation substrate of 50×40×0.3 mm having a thermalconductivity of 90 W/mK was prepared by adding Y₂O₃ and MgO as firingassistants to a commercially available silicon nitride powder and firingthe mixture at a given temperature for a given period. Separately, acommercially available pure copper plate (oxygen-free copper of purecopper composition or tough pitch copper, 80×50×3 mm: radiation plate)having a thermal conductivity of 390 W/mK was prepared.

On the other hand, a mixture of AlN pulverized powder (average particlediameter: 50 μm) and Ti powder (average particle diameter: 44 μm) wasplaced, followed by applying a pressure to reduce the thickness toimprove the packing rate of the particles, and this was placed on theupper surface of the above radiation plate. On the upper surface thereofwas placed a commercially available silver solder sheet (BAg-8: Ag-28Cu)and thereon was placed the above silicon nitride insulation substrate.On the upper surface thereof, was further placed a mixture of AlNpulverized powder (average particle diameter: 50 μm) and Ti powder,followed by applying pressure to reduce the thickness to improve packingrate of the particles, and moreover, on the upper surface thereof wasplaced a commercially available silver solder sheet (BAg-8: Ag-28Cu).Furthermore, a copper sheet of 0.3 mm thick was placed on the uppersurface thereof.

Then, the resulting stack was kept at 800° C. for 3 minutes in a vacuumof 0.00133 Pa and then slowly cooled to prepare a bonded body (laminatedradiation member). In this bonded body, the Cu—SiC radiation plate andthe silicon nitride insulation substrate were bonded with a compositematerial layer of AlN/silver solder present between the radiation plateand the substrate, and the silicon nitride insulation substrate and theuppermost copper sheet 0.3 mm thick were also bonded with a compositematerial layer of AlN/silver solder present therebetween.

Then, a resist for the formation of circuits was printed on the wholesurface of the thus obtained laminated radiation member, then only theportions which were not etched later were selectively cured, then theuncured portions were removed, and the exposed copper was etched with anaqueous cupric chloride solution to form a circuit pattern of theuppermost copper sheet of the laminated radiation member. Furthermore,this was washed with an aqueous acid ammonium fluoride solution andadditionally washed with water several times to remove the solderbetween the circuits.

Then, the resist was peeled off and finally the surface of the uppermostcopper sheet (=circuit sheet) was subjected to Ni—P plating to form aprotective layer, thereby obtaining a laminated radiation member.

EXAMPLE 4

Solid Solution Active Metal method/Upper Electrode Simultaneous Bonding

A silicon nitride insulation substrate of 50×40×0.3 mm having a thermalconductivity of 90 W/mK was prepared by adding Y₂O₃ and MgO as firingassistants to a commercially available silicon nitride powder and firingthe mixture at a given temperature for a given period. Separately, acommercially available pure copper plate (oxygen-free copper of purecopper composition or tough pitch copper, 80×50×3 mm: radiation plate)having a thermal conductivity of 390 W/mK was prepared.

On the other hand, a commercially available SiC particles (averageparticle diameter: 50 μm) were placed, followed by applying pressure toreduce the thickness to improve packing rate of the particles, and thiswas placed on the upper surface of the above radiation plate. On theupper surface thereof was placed a Cu—Ti hard solder (Cu-15Ti) sheet andthereon was further placed the above silicon nitride insulationsubstrate. On the upper surface thereof, were further placedcommercially available SiC particles (average particle diameter: 50 μm),followed by applying pressure to reduce the thickness to improve packingrate of the particles, and moreover, on the upper surface thereof wasplaced a Cu—Ti hard solder (Cu-15Ti) sheet. Furthermore, a copper sheet0.3 mm thick was placed on the upper surface thereof.

Then, the resulting stack was kept at 1000° C. for 30 minutes in avacuum of 0.00133 Pa and then slowly cooled to prepare a bonded body(laminated radiation member). In this bonded body, the pure copperradiation plate and the silicon nitride insulation substrate were bondedwith a composite material layer of SiC/Cu—Ti solder present between theradiation plate and the substrate, and the silicon nitride insulationsubstrate and the uppermost copper sheet of 0.3 mm thick were alsobonded with a composite material layer of SiC/Cu—Ti solder presenttherebetween.

Then, a resist for the formation of circuits was printed on the wholesurface of the thus obtained laminated radiation member, then only theportions which were not etched later were selectively cured, then theuncured portions were removed, and the exposed copper was etched with anaqueous cupric chloride solution to form a circuit pattern of theuppermost copper sheet of the laminated radiation member. Furthermore,this was washed with an aqueous acid ammonium fluoride solution andadditionally washed with water several times to remove the solderbetween the circuits.

Then, the resist was peeled off and finally the surface of the uppermostcopper sheet (=circuit sheet) was subjected to Ni—P plating to form aprotective layer, thereby obtaining a laminated radiation member.

EXAMPLE 5

Ni Plating Method/Upper Electrode Simultaneous Bonding

A sample was made in the same manner as in Example 1, except thatsilicon nitride insulation substrate of 50×40×0.635 mm having a thermalconductivity of 180 W/mK was prepared by adding Y₂O₃ as firingassistants to a commercially available silicon nitride powder and firingthe mixture at a given temperature for a given period.

EXAMPLE 6

Preparation of Upper Electrode Using Hard Solder Having a Melting PointLower Than Hard Solder for Bonding to Radiation Plate

A silicon nitride insulation substrate of 50×40×0.3 mm having a thermalconductivity of 90 W/mK was prepared by adding Y₂O₃ and MgO as firingassistants to a commercially available silicon nitride powder and firingthe mixture at a given temperature for a given period. Separately, aCu—SiC composite material (80×50×3 mm: radiation plate) having a thermalconductivity of 250 W/mK was prepared by the method disclosed inJP-A-11-029379.

Separately, the surface of commercially available SiC particles (averageparticle diameter: 50 μm) was subjected to Ni—B plating at a thicknessof about 0.5 μm by wet electroless plating. On the other hand, one sideof the above silicon nitride insulation substrate was subjected toelectroless Ni—B plating at a thickness of about 1 μm. Furthermore, oneside of the above Cu—SiC composite material radiation plate was alsosubjected to electroless Ni—B plating at a thickness of about 1 μm. Theabove Ni—B plated SiC particles were disposed on the Ni—B plated surfaceof the radiation plate, followed by applying pressure to reduce thethickness to improve packing rate of the particles. On the upper surfacethereof was placed a silver hard solder sheet (BAg-8: Ag-28Cu) andthereon was further placed the silicon nitride insulation substratesubjected to Ni—B plating on one side so that the Ni—B plated surfacecontacted the solder sheet.

Then, the resulting stack was kept at 800° C. for 3 minutes in a vacuumof 0.00133 Pa and then slowly cooled to prepare a bonded body (laminatedradiation member). In this bonded body, the Cu—SiC radiation plate andthe silicon nitride insulation substrate were bonded with a compositematerial layer of SiC/silver solder present between the radiation plateand the substrate.

Then, an Al solder (BA4004: Al-10Si-1.5Mg) sheet was placed on thesilicon nitride insulation substrate of the laminated radiation member,and thereon was placed a copper sheet 0.3 mm thick, followed by heattreating them in this state at 700° C. for 3 minutes in vacuum in thisstate to obtain a composite bonded member.

Then, a resist for the formation of circuits was printed on the wholesurface of the thus obtained laminated radiation member, then only theportions which were not etched later were selectively cured, then theuncured portions were removed, and the exposed copper was etched with anaqueous cupric chloride solution to form a circuit pattern of theuppermost copper sheet of the laminated radiation member. Furthermore,this was washed with an aqueous acid ammonium fluoride solution andadditionally washed with water several times to remove the solderbetween the circuits.

Then, the resist was peeled off and finally the surface of the uppermostcopper sheet (=circuit sheet) was subjected to Ni—P plating to form aprotective layer, thereby obtaining a laminated radiation member.

EXAMPLE 7

Preparation of Upper Electrode Using Composite Hard Solder Having aMelting Point Lower Than Hard Solder for Bonding to Radiation Plate

A bonded body (laminated radiation member) in which the Cu—SiC radiationplate and the silicon nitride insulation substrate were bonded with acomposite material layer of SiC/silver solder present between theradiation plate and the substrate was made in the same manner as inExample 6, except that both sides of the silicon nitride insulationsubstrate were subjected to electroless Ni—B plating at a thickness ofabout 1 μm.

Then, the above Ni—B plated SiC pulverized powder was placed on thesurface of the silicon nitride insulation substrate which was subjectedto electroless Ni—B plating of about 1 μm thick in the above laminatedradiation member, followed by applying pressure thereto to reduce thethickness to improve packing rate of particles. On the upper surfacethereof was placed a commercially available aluminum solder sheet(BA4004: Al-10Si-1.5Mg), and on the upper surface thereof was furtherplaced a copper sheet of 0.3 mm thick.

Then, the resulting stack was kept at 700° C. for 3 minutes in a vacuumof 0.00133 Pa and then slowly cooled to prepare a bonded body (laminatedradiation member). In this bonded body, the Cu—SiC radiation plate andthe silicon nitride insulation substrate were bonded with a compositematerial layer of SiC/silver solder present between the radiation plateand the substrate, and the silicon nitride insulation substrate and theuppermost copper sheet 0.3 mm thick were bonded with a compositematerial layer of SiC/aluminum solder present between the substrate andthe copper sheet.

Then, a resist for the formation of circuits was printed on the wholesurface of the thus obtained laminated radiation member, then only theportions which were not etched later were selectively cured, then theuncured portions were removed, and the exposed copper was etched with anaqueous cupric chloride solution to form a circuit pattern of theuppermost copper sheet of the laminated radiation member. Furthermore,this was washed with an aqueous acid ammonium fluoride solution andadditionally washed with water several times to remove the solderbetween the circuits.

Then, the resist was peeled off and finally the surface of the uppermostcopper sheet (=circuit sheet) was subjected to Ni—P plating to form aprotective layer, thereby obtaining a laminated radiation member.

EXAMPLE 8

Active Metal Method, Cu Casting

A silicon nitride insulation substrate of 50×40×0.3 mm having a thermalconductivity of 90 W/mK was prepared by adding Y₂O₃ and MgO as firingassistants to a commercially available silicon nitride powder and firingthe mixture at a given temperature for a given period.

Separately, pressure was applied to a mixture comprising commerciallyavailable SiC particles (average particle diameter: 50 μm) andcommercially available Ti powder (average particle diameter: 44 μm) toreduce the thickness to improve packing rate of the particles, and thiswas placed on the upper surface of the above radiation plate. This wasput in a mold as shown in FIG. 3 and heated to 1100° C., followed bycasting a copper melt therein and cooling it to obtain a laminatedradiation member.

In this laminated member, the copper radiation plate of about 80×50×3 mmand the silicon nitride insulation substrate were bonded with acomposite material layer of SiC/copper present between the radiationplate and the substrate.

On the silicon nitride insulation substrate of the laminated radiationmember was printed a commercially available Ag—Cu—Ti hard solder(Ag-35Cu-1.7Ti) paste at a given thickness, and thereon was placed acopper sheet 0.3 mm thick, followed by heat treating them in this stateat 850° C. for 10 minutes in a vacuum of 0.00133 Pa to obtain acomposite bonded member.

Then, a resist for the formation of circuits was printed on the wholesurface of the thus obtained laminated radiation member, then only theportions which were not etched later were selectively cured, then theuncured portions were removed, and the exposed copper was etched with anaqueous cupric chloride solution to form a circuit pattern of theuppermost copper sheet of the laminated radiation member. Furthermore,this was washed with an aqueous acid ammonium fluoride solution andadditionally washed with water several times to remove the soldermaterial between the circuits.

Then, the resists were peeled off and finally the surface of theuppermost copper sheet (=circuit sheet) was subjected to Ni—P plating toform a protective layer, thereby making a laminated radiation member.

EXAMPLES 9 AND 10

Plating, Flame Spraying

A silicon nitride insulation substrate of 50×40×0.3 mm having a thermalconductivity of 90 W/mK was prepared by adding Y₂O₃ and MgO as firingassistants to a commercially available silicon nitride powder and firingthe mixture at a given temperature for a given period. Separately, aCu—SiC composite material (80×50×3 mm: radiation plate) having a thermalconductivity of 250 W/mK was prepared by the method disclosed inJP-A-11-029379.

Separately, surface of commercially available SiC particles (averageparticle diameter: 50 μm) was subjected to Ni—B plating at a thicknessof about 0.5 μm by wet electroless plating. On the other hand, one sideof the above silicon nitride insulation substrate was subjected toelectroless Ni—B plating at a thickness of about 1 μm. Furthermore, oneside of the above Cu—SiC composite material radiation plate was alsosubjected to electroless Ni—B plating at a thickness of about 1 μm. Theabove Ni—B plated SiC particles were disposed on the Ni—B plated surfaceof the radiation plate, followed by applying pressure to reduce thethickness to improve packing rate of the particles. On the upper surfacethereof was placed a commercially available aluminum hard solder sheet(BA4004: Al-10Si-1.5Mg) and thereon was further placed the siliconnitride insulation substrate subjected to Ni—B plating on one side sothat the Ni—B plated surface contacted the solder sheet.

Then, the resulting stack was kept at 700° C. for 3 minutes in a vacuumof 0.00133 Pa and then slowly cooled to prepare a bonded body (laminatedradiation member). In this bonded body, the Cu—SiC radiation plate andthe silicon nitride insulation substrate were bonded with a compositematerial layer of SiC/aluminum hard solder present between the radiationplate and the substrate.

Then, masking was carried out on the silicon nitride insulationsubstrate, followed by carrying out wet electroless copper plating atlower than 100° C. to form a copper circuit pattern. This was referredto as the sample of Example 9. Masking was carried out on the portionsother than circuit pattern and an Al—Si layer of about 50 μm was flamesprayed, followed by carrying out HVOF flame spraying of Cu at athickness of about 0.3 mm. After removing the masking, the surface ofthe copper circuit was made smooth by mechanical working to form acopper circuit. This was referred to as the sample of Example 10.

COMPARATIVE EXAMPLE 1

A silicon nitride insulation substrate of 50×40×0.3 mm having a thermalconductivity of 90 W/mK was prepared by adding Y₂O₃ and MgO as firingassistants to a silicon nitride powder and firing the mixture at a giventemperature for a given period. Then, on both sides thereof was printeda commercially available Ag—Cu—Ti hard solder (Ag-35Cu-1.7Ti) paste at agiven thickness, and on both sides thereof were placed copper sheets of0.3 mm thick, followed by heat treating them in this state at 850° C.for 10 minutes in a vacuum of 0.00133 Pa to obtain a composite bondedbody.

Then, a resist for the formation of circuits were printed on one side ofthe composite bonded body and was cured, then the copper was etched withan aqueous cupric chloride solution to form a circuit pattern.Furthermore, this was washed with an aqueous acid ammonium fluoridesolution and additionally washed with water several times to remove thesolder material between the circuits. Then, the surface of the metalportion was subjected to Ni—P plating to form a protective layer,thereby making a circuit substrate.

Then, the surface of the circuit substrate on which no circuits wereformed and a Cu—SiC composite material made by the method disclosed inJP-A-11-029379 (80×50×3 mm: radiation plate) were bonded by soldering.

COMPARATIVE EXAMPLE 2

Radiation Plate/Hard Solder/Substrate/Hard Solder/Circuit

A silicon nitride insulation substrate of 50×40×0.3 mm having a thermalconductivity of 90 W/mK was prepared by adding Y₂O₃ and MgO as firingassistants to a commercially available silicon nitride powder and firingthe mixture at a given temperature for a given period. Separately, aCu—SiC composite material having a thermal conductivity of 250 W/mK wasmade by the method disclosed in JP-A-11-029379 (80×50×3 mm: radiationplate).

A commercially available Ag—Cu—Ti hard solder (Ag-35Cu-1.7Ti) paste wasprinted on the above radiation plate at a given thickness, and thereonwas placed the above silicon nitride insulation substrate. Further,thereon was printed the commercially available Ag—Cu—Ti solder(Ag-35Cu-1.7Ti) paste at a given thickness and thereon was furtherplaced a copper sheet 0.3 mm thick.

Then, this was kept at 850° C. for 10 minutes in a vacuum of 0.00133 Pa,followed by slow cooling to obtain a bonded body (laminated radiationmember). In this bonded body, the Cu—SiC radiation plate and the siliconnitride insulation substrate were bonded with the Ag—Cu—Ti solder layerpresent therebetween, and the silicon nitride insulation substrate andthe uppermost copper sheet 0.3 mm thick were also bonded with theAg—Cu—Ti solder layer present therebetween.

Then, a resist for formation of circuits was printed on the wholesurface of the thus obtained laminated radiation member, then only theportions which were not etched later were selectively cured, then theuncured portions were removed, and the exposed copper was etched with anaqueous cupric chloride solution to form a circuit pattern of theuppermost copper sheet of the laminated radiation member. Furthermore,this was washed with an aqueous acid ammonium fluoride solution andadditionally washed with water several times to remove the soldermaterial between the circuits.

Then, the resist was peeled off and finally the surface of the uppermostcopper sheet (=circuit sheet) was subjected to Ni—P plating to form aprotective layer, thereby making a laminated radiation member.

COMPARATIVE EXAMPLE 3

A sample was prepared in the same manner as in Comparative Example 2,except that a silicon nitride insulation substrate of 50×40×0.635 mmhaving a thermal conductivity of 180 W/mK was prepared by adding Y₂O₃ asa firing assistant to a commercially available aluminum nitride powderand firing the mixture at a given temperature for a given period.

The thus obtained samples were subjected to a thermal cyclecharacteristics test and a heat resistance test. The results are shownin Table 1. The results of the heat resistance test are shown by arelative value assuming the value obtained in Comparative Example 1 tobe 1.0.

TABLE 1 Interface of Timing of Radiation Interface of Thermal Pre-bonding plate & insulation Thermal resistance Exam- treat- upperRadiation insulation Insulation substrate & Circuit cycle (Standardizedple ment electrode plate substrate substrate electrode electrodecharacteristics value) 1 Ni-plating Simultaneously Cu—SiC SiC/Al hard SNSiC/Al hard Cu 3200 0.9 solder solder 2 Ni-plating ″ Cu Al₂O₃/Al SNAl₂O₃/Al hard Cu 2600 0.7 hard solder solder 3 Powder ″ Cu AlN/Ag hardSN AlN/Ag hard Cu 3200 0.8 active solder solder metal 4 Solid ″ CuSiC/CuTi SN SiC/CuTi hard Cu 3000 0.8 solution hard solder solder activemetal 5 Ni-plating ″ Cu—SiC SiC/Al hard SN SiC/Al hard Cu 1800 0.9solder solder 6 Low- Later Cu—SiC SiC/Ag hard SN Al hard solder Cu 20000.9 Temp. hard solder solder for electrode 7 Composite ″ Cu—SiC SiC/Aghard SN SiC/Al hard Cu 3200 0.8 hard solder solder solder for electrode8 Casting of ″ Cu SiC/Cu composite SN AgCuTi hard Cu 2600 0.7 molten Cumaterial solder 9 Plating ″ Cu SiC/Al hard SN — Cu 1800 0.7 solder 10 Flame ″ Cu—SiC SiC/Al hard SN Al—Si Cu 2200 0.8 spraying solder Com. — —Cu—SiC Solder + Cu + AgCuTi SN AgCuTi hard Cu 500 1.0 Exa. hard solder 1solder 2 — — Cu—SiC AgCuTi hard SN AgCuTi hard Cu 100 0.8 solder solder3 — — Cu—SiC AgCuTi hard SN AgCuTi hard Cu 10 0.8 solder solder

EXAMPLE 11

A commercially available IGBT element (power semiconductor) made of Siwas bonded to the circuit electrode of the laminated radiation membermade in Example 1 by low-temperature soldering. Then, a metal wire waselectrically connected to the terminal of the IGBT element by wirebonding method and simultaneously a metal wire was also similarlyconnected to the circuit electrode. Thereafter, the laminated radiationmember on which the IGBT element was mounted was put in a package. Then,a commercially available silicone gel for potting was poured into theabove package and cured, followed by sealing the package to enhance theelectrical insulation of the laminated radiation member on which theIGBT element was mounted and to increase the mechanical reliability,thereby obtaining a power semiconductor apparatus.

As mentioned above, the laminated radiation member and the powersemiconductor apparatus according to the present invention showsubstantially no cracking caused by a difference in the thermalexpansion coefficients of the insulation substrate, the metal basecomposite material and the radiation plate, because the radiation plateand the insulation substrate are bonded with a metal base compositematerial which is high in heat resistance and radiation properties. Thisincludes a step of, if necessary, previously surface treating a bondingsurface of the radiation plate and/or the insulation substrate to assurewettability with a solder material or a metal, a step of interposingceramic particles previously surface treated to assure wettability witha solder material or a metal between the radiation plate and theinsulation substrate, a step of disposing a solder material above and/orbelow the ceramic particles, a step of heating the solder material to atemperature higher than the melting point of the solder material to meltthe solder material, a step of penetrating the molten solder materialinto spaces between the ceramic particles to react the ceramic particleswith the solder material to produce the metal base composite materiallayer. Furthermore, according to the production method of the presentinvention as mentioned above, a laminated radiation member and a powersemiconductor apparatus having the above properties can be obtained.

1. A power semiconductor apparatus comprising: a circuit electrode; alaminated radiation member comprising a radiation plate and aninsulation substrate bonded to an upper surface of said radiation plate,said circuit electrode being provided on an upper surface of saidinsulation substrate; a semiconductor chip bonded to said circuitelectrode; and a metal wire electrically connected to said semiconductorchip and a metal wire electrically connected to said circuit electrode;wherein said semiconductor chip, said laminated radiation member andsaid circuit electrode are sealed with an insulating sealer; and whereinsaid radiation plate and said insulation substrate are bonded via ametal-based composite material layer present between said radiationplate and said insulation substrate, said metal-based composite materiallayer comprising a metal-based material, surface treated ceramicparticles having a metal surface layer dispersed within said metal-basedmaterial, particles of at least one active metal selected from the groupconsisting of Ti, Hf, Nb, Ta and Zr dispersed within said metal-basedmaterial, and a reaction product between said metal-based material andsaid metal surface layer of said surface treated ceramic particles, saidreaction product comprising a metal element of said metal-based materialand a metal element of said metal surface layer of said surface treatedceramic particles, wherein said active metal particles are added to saidsurface treated ceramic particles before said surface treated ceramicparticles are dispersed within said metal-based material, and wherein apressure is applied to said surface treated ceramic particles to reducethe thickness and improve the packing rate of said surface treatedceramic particles before said surface treated ceramic particles aredispersed within said metal-based material.
 2. A power semiconductorapparatus comprising: a circuit electrode; a laminated radiation membercomprising a radiation plate and an insulation substrate bonded to anupper surface of said radiation plate, said circuit electrode beingprovided on an upper surface of said insulation substrate; asemiconductor chip bonded to said circuit electrode; and a metal wireelectrically connected to said semiconductor chip and a metal wireelectrically connected to said circuit electrode; wherein saidsemiconductor chip, said laminated radiation member and said circuitelectrode are sealed with an insulating sealer; and wherein saidradiation plate and said insulation substrate are bonded via ametal-based composite material layer present between said radiationplate and said insulation substrate, said metal-based composite materiallayer comprising a metal-based material, surface treated ceramicparticles having a metal surface layer and having an average particlediameter in a range of 10–50 μm dispersed within said metal-basedmaterial, particles of at least one active metal selected from the groupconsisting of Ti, Hf, Nb, Ta and Zr dispersed within said metal-basedmaterial, and a reaction product between said metal-based material andsaid metal surface layer of said surface treated ceramic particles, saidreaction product comprising a metal element of said metal-based materialand a metal element of said metal surface layer of said surface treatedceramic particles, wherein said active metal particles are added to saidsurface treated ceramic particles before said surface treated ceramicparticles are dispersed within said metal-based material, and wherein apressure is applied to said surface treated ceramic particles to reducethe thickness and improve the packing rate of said surface treatedceramic particles before said surface treated ceramic particles aredispersed within said metal-based material.